To link to the entire object, paste this link in email, IM or documentTo embed the entire object, paste this HTML in websiteTo link to this page, paste this link in email, IM or documentTo embed this page, paste this HTML in website

CELLULAR PROTEINS THAT INTERACT WITH THE HEPATITIS C
VIRUS F PROTEIN
by
Kamile Yuksek
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(MOLECULAR MICROBIOLOGY AND IMMUNOLOGY)
August 2008
Copyright 2008 Kamile Yuksek

Hepatitis C virus (HCV) F protein of unknown function is produced from the core protein coding region by ribosomal frameshift. It is a short lived protein with a half life of slightly more than 10 minutes. It has been reported to affect transcription of the cellular genes such as p21, p53, and c-myc, and modulate cytokine expression. Moreover, it has been shown to associate with several cellular proteins including PFD2 and MM-1. These findings suggest that the F protein may play important roles in persistent HCV infection. To identify the cellular cofactors associated with the F protein, a human liver cDNA library was screened using the F protein as a bait in yeast two hybrid system. Several cellular proteins were identified to be associated with the HCV F protein including proteasome subunit alpha3 (3), heterogeneous nuclear ribonucloprotein L, (hnRNP L), phospholipid scramblase 1 (PLSCR1), apolipoprotein(a) (apo(a)), LIM domain containing protein 1 (LIMD1), complement protein 6 (C6), and fibulin3. The interaction between 3 and the F protein as well as hnRNP L and the F protein was confirmed by GST pull downn assay, coimmunoprecipitation, and immnofluorescence staining. Amino acids 40–60 of the F protein was identified as the 3-binding domain which together with its upstream sequence could significantly destabilize the green fluorescence protein (GFP), an otherwise stable protein. Expression of 3 reduces the F protein level in cells in a dose-dependent manner. The F protein was degraded by 20S proteasome through ubiquitin-independent pathway. And this degradation pattern might be important for its regulatory activities Although the biological significance of PLSCR1, Apo(a), LIMD1, C6, and Fibulin3, is unknown, F protein inhibits the IRES mediated HCV translation in a dose dependent manner and addition of exogenous hnRNP L relieves the suppression effect of the F protein.; These results suggest that the F protein may regulate cellular function through interaction with cellular proteins, and thus contribute to pathogenesis of HCV.

CELLULAR PROTEINS THAT INTERACT WITH THE HEPATITIS C
VIRUS F PROTEIN
by
Kamile Yuksek
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(MOLECULAR MICROBIOLOGY AND IMMUNOLOGY)
August 2008
Copyright 2008 Kamile Yuksek